Get a 89-90 b2 fuel pump and replace the current pump in the tank with that. Then you can bypass the frame rail pump completely. I though I had already did that to this b2, but I must have gotten confused with another b2 I owned.

The tanks are the same, the sender itself is even the same on the 86 as the 90. In 89-90 they ditched the lo psi pump/high psi pump and went to a single high psi pump.